The isolated perfused canine brain preparation will be used to study unidirectional transport at the blood-capillary endothelial cell interface using an indicator dilution method with 22Na as the intravascular reference and 3H labeled compounds as test molecules. Cerebral glucose transport will be characterized in terms of its pH optimum, temperature, energy, and blood flow dependence. Transport processes involved in the cerebral entry of various inorganic ions, metabolites, vitamins, and drugs will be identified. Glucose transport kinetics will be studied after the BBB had been modified by either bacterial meningitis or administration of hypertonic urea. Recovery from normothermic anoxia (30 or 60 minute perfusion with blood have a PO2 of less than 10 mmHg) and ischemia (30 or 60 minutes of no perfusion) and their effect on unidirectional glucose flux, BBB integrity, cerebral 02 uptake, regional blood flow (microsphere method) metabolic control of glycolysis, high energy phosphate content and brain ultrastructure will be studied in the presence and absence of barbiturate anesthetics. Viable cerebral capillaries will be isolated and the kinetic characteristics of glucose, amino acid, and lactate transport at the brain-capillary endothelial cell interface will be determined and compared with data obtained at the blood-capillary endothelial cell interface.